From 11c256cdcd601b67fcf5611fe8aed55b9ff00143 Mon Sep 17 00:00:00 2001
From: Dokyung Song <dokyungs@google.com>
Date: Thu, 6 Sep 2018 15:49:23 -0700
Subject: sys/fuchsia: prune unused structs in syscall description generated by
 fidlgen

After generating syscall description for fidl files using fidlgen, prune
all unused structs using the exact same mechanism used by the compiler's
check for unused structs. This allows the FIDL compiler to support
modular compilation; it does not need to have global knowledge of
whether each struct is used or not.
---
 pkg/compiler/check.go    | 75 +++++++++++++++++++++++++++++-------------------
 pkg/compiler/compiler.go | 17 +++++++----
 2 files changed, 57 insertions(+), 35 deletions(-)

(limited to 'pkg/compiler')

diff --git a/pkg/compiler/check.go b/pkg/compiler/check.go
index 7b4b63fa8..087075a12 100644
--- a/pkg/compiler/check.go
+++ b/pkg/compiler/check.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/google/syzkaller/pkg/ast"
 	"github.com/google/syzkaller/prog"
+	"github.com/google/syzkaller/sys/targets"
 )
 
 func (comp *compiler) typecheck() {
@@ -371,6 +372,48 @@ func (comp *compiler) checkLenTarget(t *ast.Type, name, target string, fields []
 	comp.error(t.Pos, "%v target %v does not exist", t.Ident, target)
 }
 
+func CollectUnused(desc *ast.Description, target *targets.Target) []ast.Node {
+	comp := createCompiler(desc, target, nil)
+	comp.typecheck()
+	return comp.collectUnused()
+}
+
+func (comp *compiler) collectUnused() []ast.Node {
+	var unused []ast.Node
+
+	comp.used, _, _ = comp.collectUsed(false)
+	structs, flags, strflags := comp.collectUsed(true)
+	_, _, _ = structs, flags, strflags
+
+	for name, n := range comp.intFlags {
+		if !flags[name] {
+			unused = append(unused, n)
+		}
+	}
+	for name, n := range comp.strFlags {
+		if !strflags[name] && builtinStrFlags[name] == nil {
+			unused = append(unused, n)
+		}
+	}
+	for name, n := range comp.resources {
+		if !structs[name] {
+			unused = append(unused, n)
+		}
+	}
+	for name, n := range comp.structs {
+		if !structs[name] {
+			unused = append(unused, n)
+		}
+	}
+	for name, n := range comp.typedefs {
+		if !comp.usedTypedefs[name] {
+			unused = append(unused, n)
+		}
+	}
+
+	return unused
+}
+
 func (comp *compiler) collectUsed(all bool) (structs, flags, strflags map[string]bool) {
 	structs = make(map[string]bool)
 	flags = make(map[string]bool)
@@ -432,35 +475,9 @@ func (comp *compiler) collectUsedType(structs, flags, strflags map[string]bool,
 }
 
 func (comp *compiler) checkUnused() {
-	comp.used, _, _ = comp.collectUsed(false)
-	structs, flags, strflags := comp.collectUsed(true)
-	_, _, _ = structs, flags, strflags
-
-	for name, n := range comp.intFlags {
-		if !flags[name] {
-			comp.error(n.Pos, "unused flags %v", name)
-		}
-	}
-	for name, n := range comp.strFlags {
-		if !strflags[name] && builtinStrFlags[name] == nil {
-			comp.error(n.Pos, "unused string flags %v", name)
-		}
-	}
-	for name, n := range comp.resources {
-		if !structs[name] {
-			comp.error(n.Pos, "unused resource %v", name)
-		}
-	}
-	for name, n := range comp.structs {
-		if !structs[name] {
-			_, typ, _ := n.Info()
-			comp.error(n.Pos, "unused %v %v", typ, name)
-		}
-	}
-	for name, n := range comp.typedefs {
-		if !comp.usedTypedefs[name] {
-			comp.error(n.Pos, "unused type %v", name)
-		}
+	for _, n := range comp.collectUnused() {
+		pos, typ, name := n.Info()
+		comp.error(pos, fmt.Sprintf("unused %v %v", typ, name))
 	}
 }
 
diff --git a/pkg/compiler/compiler.go b/pkg/compiler/compiler.go
index e66da802b..2c4e81b2b 100644
--- a/pkg/compiler/compiler.go
+++ b/pkg/compiler/compiler.go
@@ -43,13 +43,9 @@ type Prog struct {
 	fileConsts map[string]*ConstInfo
 }
 
-// Compile compiles sys description.
-func Compile(desc *ast.Description, consts map[string]uint64, target *targets.Target, eh ast.ErrorHandler) *Prog {
-	if eh == nil {
-		eh = ast.LoggingHandler
-	}
+func createCompiler(desc *ast.Description, target *targets.Target, eh ast.ErrorHandler) *compiler {
 	comp := &compiler{
-		desc:         desc.Clone(),
+		desc:         desc,
 		target:       target,
 		eh:           eh,
 		ptrSize:      target.PtrSize,
@@ -72,6 +68,15 @@ func Compile(desc *ast.Description, consts map[string]uint64, target *targets.Ta
 	for name, n := range builtinStrFlags {
 		comp.strFlags[name] = n
 	}
+	return comp
+}
+
+// Compile compiles sys description.
+func Compile(desc *ast.Description, consts map[string]uint64, target *targets.Target, eh ast.ErrorHandler) *Prog {
+	if eh == nil {
+		eh = ast.LoggingHandler
+	}
+	comp := createCompiler(desc.Clone(), target, eh)
 	comp.typecheck()
 	// The subsequent, more complex, checks expect basic validity of the tree,
 	// in particular corrent number of type arguments. If there were errors,
-- 
cgit mrf-deployment